I'll check the original filler tonight, I've still got it in the car, but can't check the tank now not without removing the new filler, drilling the lock sounds like a plan to be honest.
You could always contact a dealer and see if they have some kind of master key, or knowledge to get round it
it will come out with a cheap slide hammer. make sure its a good screw in it or it will just snap off but screw it in a good three or four turns and one good tug its out youll just have to push a srew driver in the hole and turn it. dont drill it! once its out you can always stick another barrel in the hole.